18B-29 |
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Q. REN and K. L. Parkin. Dept. of Food Science, Univ. of Wisconsin, Madison, 1605 Linden Dr., A-109 Babcock Hall, Madison, WI 53706-1519 Thiosulfinates (TS), the principle organosulfur components of fresh-minced Allium preparations, are sulfhydryl reactive and responsible for some of the pharmacological and therapeutic properties of Allium species. Understanding of the relationship between their phase II enzyme inducing activity and other cellular responses would provide some insight into mechanism of action. We hypothesize that the induction response is linked to cellular changes in REDOX status. The objective was to study the phase II enzyme inducing activity of TS using Quinone Reductase (QR) as a marker, and related changes of both extracellular and intracellular free thiol levels in TS-treated cells. TS were prepared by either a model reaction system or isolation from Alliums extracts. The assay of phase II enzyme inducer potency used murine hepatoma (Hepa 1c1c7) cells cultured in 96-well microtiter plate and QR activity was determined after treatment by test sample for 48 hr. Reduced extracellular thiols were measured using 5,5'-dithiobis 2-nitrobenzoic acid (DTNB). The inclusion of DTNB in the culture medium allowed for rapid sensing of newly formed extracellular thiols in a continuous fashion in 96-well microtiter plates. Cellular GSH levels were determined by the glutathione reductase-coupled DTNB assay after lysing of cells. The 3 homologous TS, MeS(O)SMe, PrS(O)SPr and allicin, showed similar QR-inducing activities with concentrations required to double QR (CD values) around 250 µg/ml. PeS(O)SPr, PeS(O)SMe and other 1-propenyl containing thiosulfinates had CD values only around 1 µg/ml. Both extracellular and intracellular thiol levels of Hepa 1c1c7 cells increased significantly after treatment with TS. The correlation between cellular thiol levels and QR-inducing activity were also significant. These findings revealed that the modification of cellular thiol levels is associated with the bioactivity of TS in cellular systems. Modulation of REDOX status may be a central role in the broad health-promoting properties of Allium TS.
Session 18B, Food Chemistry: Antioxidant and bioactive agents
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |